今日头条中的项目编辑有个拖动item交换位置的功能,在iOS 9 中collectionView也公开了一套方法用来实现该功能,也是方便到不行.这里做一个记载.
- (BOOL)beginInteractiveMovementForItemAtIndexPath:(NSIndexPath *)indexPath;
- (void)updateInteractiveMovementTargetPosition:(CGPoint)targetPosition ;
- (void)endInteractiveMovement;
- (void)cancelInteractiveMovement;
以上api都是在iOS9才可以使用,然而也有些点要注意.
-
代理方法中的
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath; - (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath ;
这两个方法一定要实现.第一个方法可以设定特定的cell不让其移动.而第二个方法则是用来完成移动后对数据源进行处理,毕竟我们刚才的交换只是完成了动画部分.
核心代码为:
- (void)_longPressAction:(UILongPressGestureRecognizer *)sender{
UIGestureRecognizerState status = sender.state;
CGPoint p = [sender locationInView:_imageCollectionView];
NSIndexPath *indexPath = [_imageCollectionView indexPathForItemAtPoint:p];
if(!indexPath)return;
//获取cell用来做动画
UICollectionViewCell *cell = [_imageCollectionView cellForItemAtIndexPath:indexPath];
switch (status) {
case UIGestureRecognizerStateBegan:
{
NSLog(@"%d",[_imageCollectionView beginInteractiveMovementForItemAtIndexPath:indexPath]);
[UIView animateWithDuration:0.2 animations:^{
cell.transform = CGAffineTransformScale(cell.transform, 0.8, 0.8);
}];
}
break;
case UIGestureRecognizerStateChanged:
{
[_imageCollectionView updateInteractiveMovementTargetPosition:p];
}
break;
default:
{
[_imageCollectionView endInteractiveMovement];
[UIView animateWithDuration:0.2 animations:^{
cell.transform = CGAffineTransformIdentity;
}];
};
}}
